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Remembering the Montreal Protocol

As its 20th anniversary approaches, what can the landmark agreement on controlling CFCs teach those who want to control greenhouse gases?

Until the early 1970s, it could be said that, like politics, all chemistry was local. That changed in dramatic fashion with a series of discoveries concerning the global effects of a family of chemicals called chlorofluorocarbons, or CFCs. These compounds had played a key role in the midcentury chemical revolution, allowing such innovations as safe refrigeration, cheap aerosol deodorants, and widespread air conditioning. First commercialized by ­DuPont in the early 1930s under the trade name Freon, CFCs appeared to be the perfect industrial chemical: nontoxic, nonflam­mable, and odorless. But in 1973, a pair of chemists at the University of California, Irvine–Sherwood Rowland and his postdoctoral fellow Mario Molina–began to explore the fate of the CFC gases that were being emitted into the atmosphere. Molina began the investigation of CFCs in October of that year, and by Christmas, the researchers had their answer: the CFCs were breaking down in the atmospheric ozone layer, which begins 15 kilometers above the earth, ends roughly 30 kilometers later, and absorbs much of the sun’s deadly ultraviolet radiation.

Chemists Mario Molina (above left) and Sherwood Rowland, shown in 1976, calculated that CFCs used in aerosols, refrigeration, and air conditioning were destroying the ozone layer.

The researchers found that the CFCs wafted up through the lower atmosphere intact, too stable to react with the swirling brew of chemicals around them. But once they reached the mid-­stratosphere, above most of the protective layer of ozone, the intense solar radiation broke the CFC molecules apart, releasing chlorine. Two simple reactions gave Rowland and Molina concern: Cl + O3 = ClO + O2, and ClO + O = Cl + O2. That is, chlorine (Cl) reacted with ozone (O3), generating chlorine monoxide (ClO), which in turn reacted with an oxygen atom to release another chlorine; the net result was that the chlorine was destroying ozone without depleting itself. “When we found the chain reactions” occurring in the ozone layer, remembered Rowland this fall, the fate of CFCs “suddenly went from a scientific curiosity to an environmental worry.”

The next decade was a contentious one for ­Rowland and Molina, as many in the general public, the chemical industry, and even the scientific community expressed skepticism that a nontoxic gas sprayed out of a can (in the early 1970s, recalls Rowland, roughly two-thirds of CFCs were used as propellants in aerosol products, such as deodorants) could have a significant impact on the composition of the atmosphere–much less on the viability of life on earth. “If you came off the street, it seemed ludicrous that underarm deodorants might have an effect in a global way,” Rowland says.

In 1978 the United States banned the use of CFCs in most spray-can applications. But in the early 1980s, models of the atmospheric chemistry involving CFCs became more and more complex, and various questions arose over the science.

In 1985, Rowland and Molina were vindicated. British scientists using ground-based instruments spotted a gaping “hole” in the ozone layer above the Antarctic. Subsequently, NASA reported that there was a thinning of the ozone layer over the populated areas of the Northern Hemisphere. These findings proved that Rowland and Molina’s chemistry had been correct. They also provided startling evidence that industrial chemicals, emitted largely over the industrialized population centers of North America and Europe, could change the atmosphere on a global scale.

Ozone Diplomacy

This September will mark the 20th anniversary of the Montreal Protocol on Substances that Deplete the Ozone Layer, an international agreement that set a schedule for freezing and then phasing out the production of CFCs (the 1987 treaty, which mandated halving CFC production in industrial countries by 1998, was subsequently revised; CFC production was ended in the United States by 1996). The Montreal Protocol is widely considered a milestone. Even President Reagan, no friend of environmental regulations, declared it a “monumental achievement” as he signed the treaty.

Two decades later, progress toward an international agreement on controlling greenhouse gases has reached a deadlock, and comparisons are inevitable. There are, of course, differences between CFCs and the gases, including carbon dioxide, that cause global warming. Most important, the energy production that releases carbon dioxide drives the economies of both rich and poor countries. What’s more, whereas CFCs were produced by a handful of large chemical companies, carbon dioxide emissions involve many different industries and applications. Curbing greenhouse gases will be far harder and require changes that are far more economically disruptive.

But there are also striking similarities between CFCs and greenhouse gases, and lessons to be learned from the Montreal Protocol–particularly how to get multiple countries, large international corporations, and regulators to agree on a control strategy. In his 1991 book, Ozone Diplomacy, ­Richard E. Benedick, deputy assistant secretary of state for environment, health, and natural resources under President ­Reagan, described the compromises that led to the success­ of the Montreal Protocol, detailing the scientific and technological uncertainties and the political disputes that faced those negotiating it. He points out that many elements of his story, particularly the political fighting and the need to reach a consensus in the face of doubt, should be familiar to those attempting to reach an agree­ment on greenhouse gases. As ­Benedick, the chief U.S. negotiator on the Montreal Protocol, writes in the 1998 re­vised edition, “Especially to apologists of inaction on the climate front, the Montreal Protocol can be portrayed as either too simple or not replicable. But although it is obvious that the climate change issue is more complicated and difficult than that of the ozone layer, the differences are quantitative rather than qualitative.”

Indeed, in one important respect the effort to reduce greenhouse gases is fundamentally like the effort to reduce CFCs: in each case, those who want change must motivate industry, especially large corporations, to develop the technologies needed to accomplish it. One of the most notable achievements of the Montreal Protocol was that chemical companies quickly saw the market opportunities created by the agreement. By its account, DuPont, the Wilmington, DE-based chemical giant that in the mid-1980s made roughly half the CFCs produced in the United States, spent $500 million over the next few years to develop substitutes. By the early 1990s, DuPont and its industry rivals, which included some of the world’s largest chemical manufacturers, had begun to supply CFC substitutes to refrigeration and air-conditioning manufacturers, and they’d launched massive construction proj­ects to build additional capacity to produce these chemicals.

Again, the differences between CFCs and greenhouse gases are ­notable; the new compounds could, more or less, directly replace CFCs, but there are no easy substitutes for burning fossil fuels. Nevertheless, the phaseout of CFCs highlights one factor that’s crucial in order for industry to invest in the development of new technologies. By announcing a simple and unambiguous time frame for the end of CFC production, the Montreal Protocol allowed companies to rationally predict and develop markets for alternatives.

A Stern Warning

Can such simplicity be duplicated in an international agreement to control greenhouse gases? Probably not, given the complexity of the task and the great diversity of industries and technologies that need to be part of the solution. But neither should the history of the Montreal Protocol be ignored.

DuPont and the other CFC producers were ultimately motivated by the prospect of a lucrative new market; given such an incentive, their chemists and chemical engineers rushed new technologies into production with unprecedented speed. While finding alternatives to burning fossil fuels is far more difficult, the business opportunities are also far larger. The market for low-carbon energy products will reach $500 billion by 2050, according to the Stern Review on the Economics of ­Climate Change, recently released by the British Treasury.

The effectiveness of any strategy on global warming will depend on how well it creates new markets. That much was learned from the Montreal Protocol. But perhaps the greatest lesson is also one of the simplest: when science shows us a looming environmental disaster, we need to act quickly and decisively, regardless of the economic or technical uncertainties.

David Rotman is the editor of Technology Review.

The Montreal Protocol on Substances that Deplete the Ozone LayerSeptember 16, 1987

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As the editor of MIT Technology Review, I spend much of my time thinking about the types of stories and journalism that will be most valuable to our readers. What do curious, well-informed readers need to know about emerging technologies? As a… More writer, I am particularly interested these days in the intersection of chemistry, materials science, energy, manufacturing, and economics.

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